I live in south gippsland and use smoke tainted water for my orchids and garden with no ill effects yet. Our local council advises it’s o.k. for irrigation, so check your local council’s website.
https://www.southgippsland.vic.gov.au/news/article/154/smoke_taint_in_water_tanks

Eric on January 24, 2020

Would suggest you get your water tested as authorities advised tanks be emptied and disconnected from down pipes . I arrived home from holiday on Sunday the 5th of January as I drove out of the car park at Tullamarine I noticed the running gutters had a froth on them . I thought this must have been the result of a local detergent spill . As I drove out to Ringwood this frothing was apparent in all the gutters . I would suspect the froth resulted from retardant spray from aircraft . Better safe than sorry . Test or tip

Robert Clough on January 24, 2020

I filter my rainwater through two 250mm (10") particulate cartridges-5 micron- and then one carbon filter-5 micron-These take out many contaminants and larger particles so my pump does get clogged. I’ve used this method for years with no adverse effects. Btw, I have smoke contamination here as well

BRIAN COULTON on January 24, 2020

I would suggest yes because the contaminated water would contain ash which in itself is Potash. I am using the water from my tanks which have similar contamination and my orchids aren’t suffering.
Cheers,
Brian Coulton
Batemans Bay